Dispersal and retrieval site selection by mice, transport distance, cache depth, and emergence and survival of seedlings of Castanea crenata (Japanese chestnut) were investigated by a magnet-locating experiment in two habitat conditions (gap vs. forest understorey). Magnets were inserted into nuts (n = 450) and the nuts placed in the edge of forest gaps. Although wood mice (Apodemus speciosus and A. argenteus) initially buried nuts singly in shallow surface caches near the nut source, by the following spring these cached nuts were retrieved and re-cached in larger, deeper caches farther from the source, particularly in forest understories, probably to reduce the threat of pilferage. All the nuts cached in the forest understories were consumed, but 4 seedlings emerged in gaps, apparently because of lower foraging activity in the gaps by the mice. Seed size was not correlated with cache depth or cache site selection. With increasing seed size, transport distance increased, particularly in gaps, possibly due to a greater potential energy gain (relative to handling cost to the cacher), or to attempts to prevent density- or mass-dependent loss of caches by other foragers. Variable seed dispersal behaviour based on variation in seed size may influence the chances of colonization and distribution of the light-demanding Castanea trees in mosaic landscapes and may play an important role in community organization and dynamics.

Nomenclature: Ohwi & Kitagawa (1983).

Abbreviations: FU = Forest understorey; G = Gaps.